The present invention relates to a fastening means for forming a welded joint between a fastening means and a structure.
For fastening components to a metallic structure, for example, a body of a motor vehicle, fastening means are known which are welded to the metallic structure. Known fastening means comprise a holder and a connecting element. The connecting element can be a weld stud, in particular a Christmas tree stud, which is welded to the structure. A connecting element which can be welded to a component by electric arc welding is known from WO 94/03735. The connecting element is designed in the form of a resilient tube and has a longitudinal slot.
To achieve a high degree of automation, it is known to connect the connecting element to the structure by electric arc welding or resistance welding. Electric arc welding is usually carried out by the lift and strike method.
A holder which consists mainly of a substantially electrically insulating material, in particular a plastic material, is arranged on the connecting element welded to a structure. The holder which can be, for example, a line holder, is hammered or screwed onto the connecting element.
The costs of fitting a fastening element with a welded joint to a structure are relatively high. This problem has already been acknowledged. JP-A1 61-133266 proposes the use of a fastening means in which the holder is connected to the connecting element before a welded joint is formed. The holder, which consists of a substantially electrically insulating material, surrounds a connecting element consisting of a substantially electrically conductive material and having at least one contact face for making electrical contact. In particular, JP-A1 61-133266 proposes that the connecting element, which is designed in the form of a stud, should project from the holder. This creates a sufficiently large electrical contact face. However, the sphere of application of such a fastening means is restricted. The fastening means is used, in particular, for mounting fastening strips which cover the connecting element projecting from the holder.
JP-A1 61-133266 also discloses a fastening means in which the electrical contact face is formed by a projecting peripheral flange formed on the connecting element. To achieve contact between the connecting element and a contact piece of a welding device, the contact piece is tubular in design. To ensure that the tubular contact piece can be brought into electrical contact with the peripheral flange of the connecting element, it is necessary to design the flange so that it projects laterally beyond the holder. For this purpose, it is known to form the holder from a plastics material with a base body and with at least one holding element which is pivotal round an axis formed on the base body from a basic position into a locked position. However, a holder of this type is only suitable for fixing, for example, insulating mats on a body of a motor vehicle.